Long term stability of H atoms in HD-D2-He solids

Abstract

We employed en electron spin resonance (ESR) technique for investigating the long term behavior of hydrogen and deuterium atoms in the HD-D2 impurity helium solids that were created by sending a gas mixture [H2]:[D2]:[He]= 1:4:100 through a radio-frequency electrical discharge into a volume of superfluid 4He at T = 1.5 K. H and D atoms were stabilized inside nanoclusters of impurity molecules. The exchange tunneling reactions D + H2 → HD + H and D + HD→D2 + H proceeded to eliminate D atoms and increase the concentration of H atoms in the HD-D2 impurity-helium solids. Local concentrations of H atoms inside the molecular nanoclusters of order 1020 cm−3 were achieved. The high concentration of H atoms was stable during ∼ 40 hours storage of the sample at T = 1.35 K. These solids are possible candidates for collective quantum phenomena of atomic hydrogen if the Bose-Einstein degeneracy regime can be attained.